加入Apache的豬兩個別名基於一個條件

Question

我想加入兩個別名/關係，

say A has keys : a,b,c 
and B has keys : x,y,z 

所以它應該是：

C = JOIN A by a, (IF B.x matches "foo.*" then pick y else z)

如上logic.How能我這樣做？

Answer 1

我的回答：

只是基於條件的鍵，然後按該鍵

如加入。

BB = foreach B generate x,y,z,(x matches "foo.*") ? y : z as matchkey; 
C = join A by a, BB by matchkey; 
dump c;